This invention relates to self-propelled lawn mowers and particularly to rotary lawn mowers of either the riding type or the walk-behind type.
Self-propelled rotary lawn mowers typically are driven by a transmission connected to the cutter blade drive shaft. Consequently, for mowers powered by an internal combustion engine, the mower speed can be varied only by adjustment of the engine throttle. In some situations, such as cutting heavy weeds or grass or mulching leaves, high cutter blade speed and lower mower travel speed may be desired. If the engine speed is reduced to accomplish the desired slower mower speed, the blade speed is reduced and, in some cases, the reduced power of the engine at the lower speed may be insufficient to accomplish the desired cutting. In other situations, it may be desired to operate the mower at high blade and mower speeds, low blade and mower speeds, or low blade speed and high mower speed.
U.S. Pat. No. 2,947,132,--Shaw issued Aug. 2, 1960, discloses a transmission for a rotary mower of the walk behind type, which mower includes a drive shaft which is drivingly connected to a prime mover and is selectively movable into frictional engagement with the outer periphery of a pair of the mower wheels to drive the mower. The present invention is directed to an improvement whereby the mower speed can be selectively varied independently of the engine speed.
The U.S. Pat. No. 2,962,854,--Jepson--issued Dec. 6, 1960, also discloses a rotary mower of the walk-behind type including a transmission having a two-speed drive gear with concentric rings of gear teeth and a driven gear which is connected to wheel-engagable drive shaft and which can be moved axially to mesh with either of the drive gear rings for varying the mower speed.
The U.S. Pat. No. 4,081,048--Hendricks discloses a friction drive primarily for a bicycle vehicle.
The U.S. Pat. No. 2,631,458--Metzner--discloses a speed change mechanism for phonograph turntables.